Commit 9b6d3bbc authored Feb 12, 2020 by Leon Romanovsky Committed by Jason Gunthorpe Feb 13, 2020

RDMA/mlx5: Prevent overflow in mmap offset calculations

The cmd and index variables declared as u16 and the result is supposed to
be stored in u64. The C arithmetic rules doesn't promote "(index >> 8) <<
16" to be u64 and leaves the end result to be u16.

Fixes: 7be76bef ("IB/mlx5: Introduce VAR object and its alloc/destroy methods")
Link: https://lore.kernel.org/r/20200212072635.682689-10-leon@kernel.org

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

parent 9ea04d0d

drivers/infiniband/hw/mlx5/main.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2283,8 +2283,8 @@ static int mlx5_ib_mmap_offset(struct mlx5_ib_dev *dev,

		static u64 mlx5_entry_to_mmap_offset(struct mlx5_user_mmap_entry *entry)
		{
		u16 cmd = entry->rdma_entry.start_pgoff >> 16;
		u16 index = entry->rdma_entry.start_pgoff & 0xFFFF;
		u64 cmd = (entry->rdma_entry.start_pgoff >> 16) & 0xFFFF;
		u64 index = entry->rdma_entry.start_pgoff & 0xFFFF;

		return (((index >> 8) << 16) \| (cmd << MLX5_IB_MMAP_CMD_SHIFT) \|
		(index & 0xFF)) << PAGE_SHIFT;